Tuber Peeling Apparatus and Method

ABSTRACT

A method of peeling tubers includes providing a peeler device defining a cavity surrounded by a peeling mechanism, inputting tubers to be peeled into the cavity, directing electromagnetic radiation from an illumination device into the cavity, detecting electromagnetic radiation reflected into lens of a camera from tubers located in the cavity during a peeling operation by the peeling mechanism, and operating the peeler device based on the reflected electromagnetic radiation detected by the camera. Also disclosed is an apparatus for carrying out the method.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to an apparatus for peeling tubers and toa method of peeling tubers. The present invention has particularapplication to the peeling of potatoes for the manufacture of snack foodsuch as potato chips.

Description of Related Art

In the processing of edible tubers, for example potatoes, sweet potatoesor any other edible tuber, or mixture of edible tubers, for themanufacture of processed food, for example potato chips or French fries,it is known that the edible tubers need to be peeled. The tubers need tobe peeled sufficiently to remove the entire peel, otherwise the qualityof the processed food can be compromised. This particularly applies tothe manufacture of potato chips. However, if the tubers are peeledexcessively to ensure that every tuber is fully peeled, peel waste canbe excessive, and otherwise useful flesh of the tuber can be wasted,reducing production yield.

In commercial food production, for example in the manufacture of potatochips, commercial peelers have a high production rate, for example 3tonnes per hour of potatoes to be peeled. There is a problem to achievea high volume production of peeled potatoes which achieves not only ahigh and uniform product quality but also minimizes waste, and withoutreducing production rates.

U.S. Pat. No. 4,147,619 discloses an apparatus for sorting items, suchas peeled whole potatoes, which, in the absence of abnormalities,exhibit a substantially uniform light reflectivity, includes anillumination chamber through which the items to be sorted are passedsuccessively as a stream. Light sensors are focused on a cross-sectionalslice of the illumination chamber through which the items pass, each ofthese light sensors being focused on only a small portion of the slice.Electronic circuitry in conjunction with the light sensors counts thenumber of such sensors sensing abnormalities. If the number of sensorssensing abnormalities is greater than a predetermined minimum, a rejectsignal is produced. This disclosure rejects potatoes having defects.There is no improvement in the peeling operation.

U.S. Pat. No. 5,884,775 discloses a system and method of operationperforming automated optical inspection to remove peel-bearing defectivepotato pieces from a random mixture of peel-bearing defective andacceptable potato pieces use near infrared light as a source ofillumination. The system implements a method of illuminating the mixturewith near infrared light, detecting light reflected by the potato piecesunder inspection, identifying defective potato piece surface regionsbased on the detected reflections, and removing the defective items fromthe mixture. The system and method the system implements permit theinspection of peel bearing potato pieces for the presence of peelcovered defects. Again, there is no improvement in the peelingoperation.

WO-A-9311882 discloses an optical device for controlling and sortingindividual objects in free fall comprises a laser scanner located on theperiphery of a control zone whose reflected light is collected from allsides by the ends of light guides and transmitted to a controller forevaluation purposes. The controller controls a sorting device downstreamof the control zone according to predetermined control criteria. A lightguide strip which surrounds the control area captures the reflectedlight is controlled according to the direct light sensed. This device isparticularly useful for sorting peeled potatoes and wet products. Again,there is no improvement in the peeling operation.

Consequently, there is a need for an improved method and apparatus forpeeling edible tubers on a commercial scale.

In addition, there is a need to reduce or minimize waste of tuber fleshto provide an increased yield of peeled tuber product obtained from agiven mass of the unpeeled tuber product.

There is a further need to provide a peeling apparatus which can achievethese objectives without significant capital expense, and preferably beretrofitting existing peelers with an enhanced peeling module.

The present invention aims at least partially to meet these needs.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides an apparatus for peelingtubers, the apparatus comprising:

-   -   a peeler device defining a cavity surrounded by a peeling        mechanism, the peeler device having an input connected to the        cavity for inputting tubers to be peeled into the cavity;    -   an illumination device for directing electromagnetic radiation        into the cavity;    -   a camera having a lens defining a field of view, the field of        view being oriented into the cavity, the camera being arranged        for detecting electromagnetic radiation reflected into the lens        from tubers located in the cavity during a peeling operation by        the peeling mechanism; and    -   an operating system for operating the peeler device based on the        reflected electromagnetic radiation detected by the camera, the        operating system comprising:        -   a sampler for sequentially measuring a plurality of            intensity values of the detected electromagnetic radiation;        -   a comparator for comparing the measured intensity values to            determine a rate of change of the measured intensity values;            and        -   a controller for controlling the peeler device in response            to the rate of change of the measured intensity values.

In a second aspect the invention provides a method of peeling tubers,the method comprising the steps of:

-   -   a. providing a peeler device defining a cavity surrounded by a        peeling mechanism;    -   b. inputting tubers to be peeled into the cavity;    -   c. directing electromagnetic radiation from an illumination        device into the cavity;    -   d. detecting electromagnetic radiation reflected into lens of a        camera from tubers located in the cavity during a peeling        operation by the peeling mechanism; and    -   e. operating the peeler device based on the reflected        electromagnetic radiation detected by the camera.

Optional or preferred features are defined in the respective dependentclaims.

In preferred embodiments, the present invention provides a peeler devicewith an operating system for controlling the peeling function so thepeeling function is terminated after a preset degree of peeling has beenachieved. Both under-peeling, which reduces the quality of the peeledproduct, and over-peeling, which increases tuber wastage withoutincreasing the quality of the peeled product, can be avoided.

The peeling function can be controlled so that a precise and uniformdegree of peeling is achieved within a batch of tubers, with the peelingcontrol being achieved in real-time and dynamically during the peelingoperation.

A high quality peeled tuber product can be consistently achieved withoutexcessive product wastage.

The operating system for controlling the peeling function can readily befitted, or retro-fitted, to a peeler device, such as a currentcommercial peeler.

In a third aspect, the present invention also provides a device forsorting tubers, the device comprising: a plurality of sorting zonesserially arranged along a conveying direction from a tuber supply end,wherein each sorting zone comprises an array of mutually aligned barsforming a grid, the bars in each sorting zone being mutually separatedby a respective spacing distance, wherein the spacing distance in thefirst sorting zone, which is located towards the tuber supply end, issmaller than the spacing distance in the second sorting zone which isdownstream, along the conveying direction, from the first sorting zone,whereby tubers smaller than a first threshold size fall though the barsof the first sorting zone and tubers larger than the first thresholdsize are conveyed along the bars of the first sorting zone to the secondsorting zone.

In a fourth aspect, the present invention further provides a method ofsorting tubers, the method comprising the steps of:

-   -   i. providing a tuber sorting device comprising a plurality of        sorting zones serially arranged along a conveying direction from        a tuber supply end, wherein each sorting zone comprises an array        of mutually aligned bars forming a grid, the bars in each        sorting zone being mutually separated by a respective spacing        distance, wherein the spacing distance in the first sorting        zone, which is located towards the tuber supply end, is smaller        than the spacing distance in the second sorting zone which is        downstream, along the conveying direction, from the first        sorting zone, and    -   ii. supplying tubers at from a tuber supply end whereby the        tubers are conveyed along the conveying direction, whereby        tubers smaller than a first threshold size fall though the bars        of the first sorting zone and tubers larger than the first        threshold size are conveyed along the bars of the first sorting        zone to the second sorting zone.

Again, optional or preferred features are defined in the respectivedependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only with reference to the following drawings, in which:

FIG. 1 is a schematic side view of an apparatus for peeling tubersaccording to an embodiment of the present invention;

FIG. 2 is a close-up perspective view of the tuber sorting device ofFIG. 1;

FIG. 3 is a graph showing the relationship between reflectedelectromagnetic radiation and time according to a first example of themethod of peeling tubers using the apparatus of FIG. 1; and

FIG. 4 is a graph showing the relationship between reflectedelectromagnetic radiation and time according to a first example of themethod of peeling tubers using the apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The accompanying figures are schematic and are not intended to be drawnto scale. In the figures, each identical, or substantially similarcomponent that is illustrated in various figures is represented by asingle numeral or notation. For purposes of clarity, not every componentis labeled in every figure. Nor is every component of each embodiment ofthe invention shown where illustration is not necessary to allow thoseof ordinary skill in the art to understand the invention.

Referring to FIGS. 1 and 2, there is shown an apparatus 2 for peelingtubers according to an embodiment of the present invention. The tubersmay comprise any edible tuber, or mixture of edible tubers, and thepresent invention has particular application to the peeling of potatoes,for example for the manufacture of processed food, typically potatochips or French fries.

The apparatus 2 comprises a peeler device 4 defining a cavity 6surrounded by a peeling mechanism 8. The peeler device 4 has an input 10connected to the cavity 6 for inputting tubers to be peeled into thecavity 6.

The peeling mechanism 8 is typically a known commercially used device,and comprises a rotatable cylinder 12 having an abrasive innercylindrical surface 14. When the peeling mechanism 8 is operated, thetubers within the cavity 6 are urged radially outwardly under acentrifugal force as a result of rotation of the rotatable cylinder 12,and the tubers are abraded against the abrasive inner cylindricalsurface 14. A flow of water (not shown) into the cavity 6 can wash awaythe abraded peel material.

In accordance with this invention, the peeler device 4 is provided withan operating system for controlling the peeling function so the peelingfunction is terminated after a preset degree of peeling has beenachieved. Both under-peeling, which reduces the quality of the peeledproduct, and over-peeling, which increases tuber wastage withoutincreasing the quality of the peeled product, can be avoided. Thepeeling function can be controlled so that a precise and uniform degreeof peeling is achieved within a batch of tubers, with the peelingcontrol being achieved in real-time and dynamically during the peelingoperation. A high quality peeled tuber product can be consistentlyachieved without excessive product wastage.

Accordingly, an illumination device 20 is provided above the cavity 6for directing electromagnetic radiation into the cavity 6. Theillumination device 20 is adapted to generate electromagnetic radiationwithin a wavelength range which can permit the reflected radiation toindicate the properties of the peeled product. The electromagneticradiation can be within the visible region of the electromagneticspectrum, or in the infrared (IR) or ultraviolet (UV) regions of theelectromagnetic spectrum.

The illumination device 20, typically has any suitable form ofillumination element, such as a light emitting diode (LED) or anincandescent filament, is adapted to generate electromagnetic radiationwithin the wavelength range of from 490 to 780 nm, this being within thevisible region of the electromagnetic spectrum.

In one embodiment, the illumination device 20 is adapted to generateelectromagnetic radiation within the wavelength range of from 490 to 570nm, and the electromagnetic radiation may be green in colour.

In another embodiment, the illumination device 20 is adapted to generateelectromagnetic radiation within the wavelength range of from 620 to 780nm, and the electromagnetic radiation may be red in colour.

It has been found that, when controlling the peeling of potatoes inaccordance with the illustrated embodiment of the present invention, redor green light has a higher sensitivity to indicating the peeling degreeusing reflected light as compared to, for example, blue light.

A camera 22 is provided above the cavity 6. The camera 22 has a lens 24defining a field of view F. The field of view F is oriented into thecavity 6. The camera 44 is arranged for detecting electromagneticradiation reflected into the lens 24 from tubers T located in the cavity6 during a peeling operation by the peeling mechanism 8.

Preferably, the illumination device 20 and the camera 22 are surroundedby a tubular enclosure 21, for example composed of stainless steel,having a lower window 23, for example composed of a polymer such asPMMA, which protects the illumination device 20, the camera 22 and inparticular the lens 24 from debris produced during the peelingoperation. The window 23 is inclined at an angle to the optical axis ofthe camera 22, and in use is inclined to the vertical, and can readilybe cleaned after a peeling operation.

The apparatus 2 further comprises a processor-controlled operatingsystem 26 for operating the peeler device 4 based on the reflectedelectromagnetic radiation detected by the camera 22.

The operating system 26 comprises a sampler 28 for sequentiallymeasuring a plurality of intensity values of the detectedelectromagnetic radiation. The sampler 28 is adapted to measure a presetnumber of intensity values of the detected electromagnetic radiation.Typically the preset number of intensity values is from 5 to 50, or from10 to 30. The sampler 28 is adapted to measure the preset number ofintensity values over a preset time period. The preset time period maybe from 0.5 to 2 seconds typically from 0.5 to 1.5 seconds, for exampleabout 1 second.

The operating system 26 further comprises a calculator 30 forcalculating an average intensity value representing an average intensityvalue associated with a particular first time period.

The operating system 26 further comprises a comparator 32 for comparingthe measured intensity values to determine a rate of change of themeasured intensity values.

The calculator 30 is arranged to output the average intensity value tothe comparator for comparison against at least one other calculatedaverage intensity value associated with a different first time periodthan the particular first time period.

The calculator 30 is arranged to output to the comparator from 2 to 10average intensity values, for example from 2 to 6 average intensityvalues.

The calculator 30 is arranged to output to the comparator 32 theplurality of average intensity values which represent the intensityvalues measured over a second time period. The second time period may befrom 1 to 10 seconds, typically from 1 to 5 seconds, for example from 2to 4 seconds. A preferred value is 3 seconds.

The operating system 26 further comprises a controller 34 forcontrolling the peeler device 4 in response to the rate of change of themeasured intensity values. The controller 34 is adapted to control thepeeler device 4 in response to the rate of change of the measuredintensity values when, for example, the rate of change is less than 10%of the measured intensity values, typically less than 5% of the measuredintensity values, more typically less than 2% of the measured intensityvalues, for example less than 1% of the measured intensity values.

In other words, the controller 34 is adapted to control the peelerdevice 4 when the rate of change of the average intensity values is solow that the averaged intensity value changes over the second timeperiod, for example 3 seconds, by less than 10%, typically less than 5%,more typically less than 2%, for example less than 1%, over the secondtime period. Such a low change in the average intensity value over agiven time period indicates that the reflection intensity is levellingoff to the final constant value, independent of the actual finalconstant value of the reflection intensity, which can vary from batch tobatch of tubers.

In one embodiment, the operating system 26 is adapted to terminateoperation of the peeler device 4, either immediately or following afirst predetermined time delay, after the rate of change of the measuredintensity values reaches a first preset threshold value.

In another embodiment, the operating system 26 is adapted to causepeeled tubers to be outputted from the cavity 6, either immediately orfollowing a first predetermined time delay, after the rate of change ofthe measured intensity values reaches a first preset threshold value.

In a further embodiment, the operating system 26 is adapted to terminateoperation of the peeler device 4, or to cause peeled tubers to beoutputted from the cavity 6, either immediately or following a secondpredetermined time delay, when the rate of change of the measuredintensity values is below a second preset threshold value at the expiryof a minimum time period from commencement of a peeling cycle by thepeeler device 4.

The operating system 26 may be configured to terminate operation of thepeeler device 4 by switching off power to a drive motor 35 for thepeeler device 4. For example, a control signal may be sent from thecontroller 34 to the drive motor 35 along a control line 37.

In a preferred embodiment, the operating system 26 is adapted to detecta spike of reflected electromagnetic radiation detected by the camera 8,and to output a calibration signal in response thereto.

Referring to FIG. 2, the apparatus 2 further comprises a tuber sortingdevice 36 coupled, directly or indirectly, to the input 10 of the peelerdevice 4. The tuber sorting device 36 can feed tubers of a selected sizerange to the peeler device 4.

The tuber sorting device 36 comprises a plurality of sorting zones 38,40, 42 serially arranged along a conveying direction C from a tubersupply end 44. Each sorting zone 38, 40, 42 comprises an array ofmutually aligned bars 46, 48, 50 forming a grid 52. The grid 52 isinclined downwardly from the tuber supply end 44, and the bars 46, 48,50 are rotated or otherwise moved by a drive mechanism 58, to cause thetubers to move along the bars 46, 48, 50 from the tuber supply end 44.The bars 46, 48, 50 may be eccentrically mounted at an upstream end 66,68, 70 thereof to a drive device 60, 62, 64 and the downstream end 72,74 76 of the bars 46, 48, 50 may be free.

The bars 46, 48, 50 in each sorting zone 38, 40, 42 are mutuallyseparated by a respective spacing distance d1, d2, d3. The spacingdistance d1 in the first sorting zone 38, which is located towards thetuber supply end 44, is smaller than the spacing distance d2 in thesecond sorting zone 40 which is downstream, along the conveyingdirection C, from the first sorting zone 38. Accordingly, in operation,tubers smaller than a first threshold size d1 fall though the bars 46 ofthe first sorting zone 38 and tubers larger than the first thresholdsize d1 are conveyed along the bars 46 of the first sorting zone 38 tothe second sorting zone 40.

Typically, the second sorting zone 40 is configured such that in thesecond sorting zone 40 tubers smaller than a second threshold size d2fall though the bars 48 of the second sorting zone 40 and tubers largerthan the second threshold size d2 conveyed along the bars 48 of thesecond sorting zone 40 to a third sorting zone 42. The third sortingzone 42 may permit all of the remaining tubers to be fed to the peelerdevice 4. Alternatively, the third sorting zone 42 may correspondinglysort tubers smaller than a third threshold size d3 by falling though thebars 50 of the third sorting zone 52 and tubers larger than the thirdthreshold size d3 are conveyed along the bars 50 of the third sortingzone 52 to a fourth sorting zone (not shown) or to an output end 54 ofthe tuber sorting device 36.

The spacing distances d1, d2, d3 are selected to provide desiredindividual potato size populations for subsequent processing, e.g.peeling. For example, the spacing distance d1 in the first sorting zonemay be 60 mm +1-20 mm, the spacing distance d2 in the second sortingzone may be 140 mm +/− 20 mm, and the spacing distance d3 in the thirdsorting zone may be 200 mm +/− 20 mm.

In the illustrated embodiment of FIG. 2, the spacing distances d1, d2,d3 are, respectively, 60 mm, 140 mm and 200 mm. Therefore the firstsorting zone 38 sorts out tubers of dimension of 60 mm or less, thesecond sorting zone 40 sorts out tubers of dimension greater than 60 mmto up to 140 mm, and the third sorting zone 42 sorts out tubers ofdimension greater than 140 mm to up to 200 mm. The three sorting zones38, 40, 42 serially arranged along the conveying direction C can sort aninitial tuber supply having various tuber dimensions within the range offrom 0 to 200 mm into three sorted groups of different tuber dimensions.This means that each group has a more statistically uniform dimensionalrange, which has been found to enhance the uniformity of the peelingoperation for any give batch of tubers.

Referring back to FIG. 1, which shows a single sorting zone of thesorting device 36, a hopper 56 is disposed beneath a respective sortingzone 38, 40, 42 of at least one of the plurality of sorting zones 38,40, 42 for receiving tubers falling though the bars 46, 48, 50 of therespective sorting zone 38, 40, 42. In the preferred embodiment, aplurality of the peeler devices 4 and a plurality of hoppers 56 areprovided, each hopper 56 being connected to the input of a respectiveone, or more than one, of the peeler devices 4. Typically, each hopper56 is connected to the input 10 of the respective peeler device(s) 4. Inthe preferred embodiment, each hopper 56 is connected to the input 10 oftwo peeler device(s) 4.

The method of peeling tubers will now be described with reference toFIG. 3 which is a graph showing the relationship between reflectedelectromagnetic radiation and time according to a first example of themethod of peeling tubers using the apparatus of FIG. 1.

In the method of peeling tubers, tubers (e.g. potatoes) to be peeled,typically as a batch of a pre-defined weight, are inputted through theinput 10 into the cavity 6 of the peeler device 4. The peeling mechanism8 is operated by rotation, causing the tubers to be peeled by abrasionagainst the abrasive inner cylindrical surface 14.

During the peeling operation, the illumination device 20 directselectromagnetic radiation into the cavity 6, and thereby onto the tubersthat are being progressively peeled. Simultaneously, the camera 22detects electromagnetic radiation that has been reflected into lens 24of the camera 22 from the tubers located in the cavity 6 during thepeeling operation by the peeling mechanism 8.

As described above, the illumination device 20 preferably emitselectromagnetic radiation within the wavelength range of from 490 to 570nm, and the electromagnetic radiation may be green in colour.Alternatively, in another preferred embodiment, the illumination device20 emits electromagnetic radiation within the wavelength range of from620 to 780 nm, and the electromagnetic radiation may be red in colour.It has been found that, when controlling the peeling of potatoes inaccordance with the illustrated embodiment of the present invention, redor green light has a higher sensitivity to indicating the peeling degreeusing reflected light as compared to, for example, blue light.

The initial unpeeled tubers have a low reflectivity for theelectromagnetic radiation, whereas in contrast the final peeled tubershave a high reflectivity for the electromagnetic radiation. The increaseof detectable reflected radiation during the peeling operation isutilized to control the peeling operation so that the peeling operationis terminated after a preset degree of peeling has been achieved. Theoperation of the peeler device is therefore controlled based on thereflected electromagnetic radiation detected by the camera.

In particular, it has been found by the present inventors, afterextensive research work, that the reflection intensity has a particularrelationship with peeling time during the peeling operation and that thereflection intensity varies from batch to batch for the tubers, and canvary between different tuber varieties.

In particular, tubers do not have a consistent reflection intensity fordifferent batches of tubers for the same variety; for example the colourof the flesh of potatoes of the same variety can vary from batch tobatch and in particular can vary depending on the harvest or storagetime of the potatoes (as potatoes age during storage the flesh colourchanges, and typically darkens with age).

Furthermore, different tuber varieties have different skin colours anddifferent flesh colours.

Consequently, it is not feasible, in order to achieve accurate peelingcontrol, simply to measure the reflection intensity and terminate thepeeling operation after a minimum reflection intensity threshold hasbeen achieved, because the threshold can varies from batch to batch, andno common threshold can be reliably utilized for sequential peelingoperations achieving a high level of accuracy for the degree of peeling,thereby avoiding under-peeling, while avoiding wastage as a result ofover-peeling.

The present invention is predicated on the finding that in order toachieve a high level of accuracy for the degree of peeling, therelationship between the reflection intensity and time should bedetermined and an analysis of the rate of change of the reflectionintensity with time is determined and analyzed to provide a signal whichis utilized to terminate the peeling operation.

FIG. 3 is a graph for the variation of reflection intensity with timeduring the peeling operation for a typical potato variety used in themanufacture of potato chips, and which has light coloured skin.

Initially, in a first phase I, the reflection intensity has a constantlow initial value. This is because the incident electromagneticradiation from the illumination device 20 is reflected of the relativelydark skin, as compared to the flesh, of the potatoes, and also the inputpotatoes to be peeled may also be covered with mud or earth deposits.

Subsequently, in a second phase II, the skins of the potatoes areprogressively removed by the peeling operation. As shown in FIG. 3, thereflection intensity increases, substantially linearly, from the lowinitial value as the potatoes are progressively peeled. As tubers skinis removed and the lighter coloured flesh is progressively revealed, thereflection intensity increases.

The rate of change of the reflection intensity in the second phase IIcan be represented by the angle α between the plot of the reflectionintensity and the Y axis (ordinate); the smaller the angle α, the fasterthe peeling operation occurs. The angle α varies between differentbatches of the same potato variety and between different potatovarieties.

Thereafter, in a third phase III, substantially all of the skins of thepotatoes have been removed by the peeling operation. As shown in FIG. 3,the reflection intensity starts to level off to a final reflectionintensity RI, representing the fully peeled status when only peeledflesh is present and all of the potato skin has been peeled away andremoved. As discussed above, final reflection intensity RI variesbetween different batches of the same potato variety and betweendifferent potato varieties.

After the RI value has been achieved, there is a fourth phase IV inwhich the measured intensity remains constant while the peeled tubersare in the cavity 6 but the peeling operation has stopped. Obviously, ifthe peeled tubers are emptied from the cavity 6 after peeling themeasured reflection intensity value would vary accordingly.

In the present invention, the rate of change of the reflection intensitywith time which is measured in phase III is used to control the peelingoperation.

In particular, during the peeling operation a plurality of reflectionintensity values of the detected electromagnetic radiation aresequentially measured. For example, the reflection intensity is measuredat a rate of from 5 to 50, or from 10 to 30, typically 20, measurementsper second.

From this sequence, a preset number of intensity values of the detectedelectromagnetic radiation over a preset time period (called herein the“first time period”) is measured by the sampler 28, and an averageintensity value, representing an average intensity value associated witha particular first time period, is calculated by the calculator 30. Thepreset number of intensity values is typically from 5 to 50, preferablyfrom 10 to 30, for example 20 and typically the preset time period isfrom 0.5 to 2 seconds, preferably from 0.5 to 1.5 seconds, for exampleabout 1 second.

In the illustrated embodiment, the sampler measures 20 samplemeasurements of the reflection intensity over a 1 second period.

Then the calculator 30 calculates from the plurality of samples measuredin the given time period (e.g. 20 samples measured in 1 second) anaverage reflection intensity value in that time period. This is achievedby a simple averaging algorithm in the calculator 30.

This provides a sequence of average intensity values over a sequence ofsuccessive time periods.

Thereafter, in the comparator 32 the average intensity value of a giventime period is compared against at least one other calculated averageintensity value associated with a different first time period than thatparticular given time period. This comparison is used to determine arate of change of the measured intensity values.

In particular, in the illustrated embodiment from 2 to 10 averageintensity values are used to determine a rate of change of the measuredintensity values. Preferably, from 2 to 6 average intensity values, forexample 3 average intensity values, are used to determine a rate ofchange of the measured intensity values.

The plurality of average intensity values represent the intensity valuesmeasured over a cumulative time period (called herein the “second timeperiod”) which is sufficiently long to ensure that the rate of change ofthe measure intensity with time is accurately detected to enable thelevelling off of the reflection intensity, representative of the desireddegree of peeling, to be reliably and consistently detected. Typically,the second time period is from 1 to 10 seconds, preferably from 1 to 5seconds, more preferably from 2 to 4 seconds, for example about 3seconds.

In the illustrated embodiment, the sampler 28 measures 20 samplemeasurements of the reflection intensity over a 1 second period (thisbeing the first time period) and an average intensity value iscalculated from those 20 sample measurements by the calculator 30. Thenthree successive 1 second periods, making a total of three seconds (thisbeing the second time period), are used in the comparator 32 todetermine the rate of change of the average intensity values over thattotal time period.

The determined rate of change is used by the controller 34 to controlthe termination of the peeling function.

The peeler device 4 is controlled in response to the rate of change ofthe measured intensity values. In particular, as the intensity levelsoff to a final constant reflection intensity value RI, the rate ofchange of the measured intensity values is progressively reduced inphase III. The peeler device may be controlled to terminate the peelingoperation when the rate of change of the measured intensity valuesreaches a minimum threshold, for example is below a given rate ofchange.

In the illustrated embodiment, the peeler device 4 is controlled inresponse to the rate of change of the measured intensity values when therate of change is less than 10% of the measured intensity values.Typically, the peeler device 4 is controlled in response to the rate ofchange of the measured intensity values when the rate of change is lessthan 5%, less than 2%, or less than 1%, of the measured intensityvalues.

When the rate of change of the measured intensity values reaches theminimum threshold, the peeling operation may be terminated eitherimmediately or following a predetermined time delay, for example up to 5seconds. The peeling operation may be terminated by terminating theoperation of the peeling mechanism 8 or by causing peeled tubers to beoutputted from the cavity 6, in either case either immediately orfollowing a first predetermined time delay, after the rate of change ofthe measured intensity values reaches a first preset threshold value.

After a typical minimum time period within which it is assured that thepeeling operation will have been terminated using the peeling operationcontrol as described above, for example about 60 seconds, for a typicalcommercial potato peeler device having a 50 kg batch capacity andcapable of producing 3 tonnes per hour of peeled potatoes, the lenswindow 23 is cleaned, for example by a spray of water or by a cleaningdevice.

This causes a spike S, shown in FIG. 3, of the measured intensity to bedetected, since the electromagnetic radiation has a high level ofreflection from any water or cleaning device located immediatelyadjacent to the window 23. The measured spike can be utilized to confirmthat the illumination device 20 and camera 22 are functioning correctly,and therefore a subsequent peeling cycle on a further batch of tuberscan be commenced, and thereby to calibrate the sensitivity of the camera22 to detecting the reflected electromagnetic radiation.

FIG. 3 shows a typical plot for white and young potatoes exhibiting asignificant and rapid increase in the reflection intensity during thepeeling operation which levels off to a final constant reflectionintensity value RI.

In contrast, FIG. 4 shows a typical plot for red or older potatoes whichexhibit only a slower and smaller a significant increase in thereflection intensity during the peeling operation which does not leveloff to a final constant reflection intensity value RI. For suchpotatoes, the rate of change of the reflection intensity in the secondphase II can be represented by the angle β between the plot of thereflection intensity and the Y axis (ordinate); the angle β is largerthan the angle α, indicating slower change in the reflection intensityas peeling progresses, although the peeling operation would havesubstantially the same skin removal rate irrespective of flesh or skincolour for otherwise identical potato batches. The angle β variesbetween different batches of the same potato variety and betweendifferent potato varieties. For such potatoes, a third phase III,exhibiting levelling off to a final constant reflection intensity valueRI, is absent, and a fourth phase IV, exhibiting a final constantreflection intensity value RI, is absent.

For such tubers exhibiting a second phase II exhibiting a lower rate ofchange of the reflection intensity and no third phase III, the methodand apparatus of the invention can still be utilized.

In particular, the peeler device 4 may still be controlled to terminatethe peeling operation when the rate of change of the measured intensityvalues reaches a minimum threshold, for example is below a given rate ofchange, and the rate of change is typically higher used for the potatoesof FIG. 3.

For example, the minimum threshold may be less than 10% or less than 5%,of the measured intensity values. Furthermore, when the rate of changeof the measured intensity values reaches the minimum threshold, thepeeling operation may be terminated either by terminating operation ofthe peeling mechanism 8, or by causing peeled tubers to be outputtedfrom the cavity, either immediately or following a predetermined timedelay, for example up to 5 seconds. A higher sampling rate and/or alonger second time period may be used to analyze the rate of change ofthe reflection intensity when the relationship in second phase II is asshow in FIG. 4.

The batch of tubers supplied to the peeler device 4 is pre-sorted tohave a desired size range, so that in any given batch of tubers to bepeeled the tubers have substantially the same dimensions. Thispre-sorting protocol is utilized to minimize peel waste and enhance peeluniformity and quality.

A batch of tubers inputted to each peeler device 4 therefore has aselected size range.

An initial tuber supply is sorted in the tuber sorting device 36described above, which is coupled, directly or indirectly, to the input10 of the peeler device 4 or pair of peeler devices 4.

The supply of tubers is fed in to the sorting device 36 at the tubersupply end. The tubers pass along the first sorting zone 38. Tuberssmaller than the first threshold size d1 fall though the bars 46 of thefirst sorting zone 38 into a hopper 54. The hopper 54 feeds the sortedtubers of the selected size range d1 to a respective peeler device 4 orpair of peeler devices 4.

Tubers larger than the first threshold size d1 are conveyed along thebars 46 of the first sorting zone 38 to the second sorting zone 40.Typically, the second sorting zone 40 is configured such that in thesecond sorting zone 40 tubers smaller than the second threshold size d2fall though the bars 48 of the second sorting zone 40 into a secondhopper 54. The second hopper 54 feeds the sorted tubers of the selectedsize range d2 to a second respective peeler device 4 or pair of peelerdevices 4.

Tubers larger than the second threshold size d2 are conveyed along thebars 48 of the second sorting zone 40 to the third sorting zone 52. Thethird sorting zone 52 may permit all of the remaining tubers to be fedto a respective third peeler device 4 or pair of peeler devices 4.Alternatively, the third sorting zone 52 may correspondingly sort tuberssmaller than the third threshold size d3 by falling though the bars 50of the third sorting zone 52 and tubers larger than the third thresholdsize d3 are conveyed along the bars 50 of the third sorting zone 52 to afourth sorting zone (not shown) or to the output end 54 of the tubersorting device 36.

The present invention has particular application to the peeling ofpotatoes that are subsequently cut into potato slices for themanufacture of potato chips (crisps). It has been found by the presentinventors that the apparatus and method of the preferred embodiments ofthe present invention, using reflected electromagnetic radiationdynamically to control the termination of the peeling cycle, can achievea yield gain, measured as reduced loss of potato flesh as a result ofover-peeling, of at least 1 wt %. For a typical commercial peeler usedin a potato chip manufacturing line, this represents a saving of atleast 30 kg per hour of potato flesh which otherwise would be lost to apeel waste stream. Moreover, the apparatus and method of the preferredembodiments of the present invention, using reflected electromagneticradiation dynamically to control the termination of the peeling cycle,can achieve a more uniform peeling across plural batches of potatoes, ofvarying age and of different varieties.

Various modifications to the embodiments of the present invention asdescribed above will be apparent to those skilled in the art and suchmodifications are intended to fall within the scope of the presentinvention as defined in the appended claims.

1.-92. (canceled)
 93. An apparatus for peeling tubers, the apparatuscomprising: a peeler device defining a cavity surrounded by a peelingmechanism, the peeler device having an input connected to the cavity forinputting tubers to be peeled into the cavity; an illumination devicefor directing electromagnetic radiation into the cavity; a camera havinga lens defining a field of view, the field of view being oriented intothe cavity, the camera being arranged for detecting electromagneticradiation reflected into the lens from tubers located in the cavityduring a peeling operation by the peeling mechanism; and an operatingsystem for operating the peeler device based on the reflectedelectromagnetic radiation detected by the camera, the operating systemcomprising: a sampler for sequentially measuring a plurality ofintensity values of the detected electromagnetic radiation; a comparatorfor comparing the measured intensity values to determine a rate ofchange of the measured intensity values; and a controller forcontrolling the peeler device in response to the rate of change of themeasured intensity values.
 94. The apparatus of claim 93, wherein theoperating system is adapted to terminate operation of the peeler device,either immediately or following a first predetermined time delay, afterthe rate of change of the measured intensity values reaches a firstpreset threshold value.
 95. The apparatus of claim 93, wherein theoperating system is adapted to cause peeled tubers to be outputted fromthe cavity, either immediately or following a first predetermined timedelay, after the rate of change of the measured intensity values reachesa first preset threshold value.
 96. The apparatus of claim 93, whereinthe operating system is adapted to terminate operation of the peelerdevice, or to cause peeled tubers to be outputted from the cavity,either immediately or following a second predetermined time delay, whenthe rate of change of the measured intensity values is below a secondpreset threshold value at the expiry of a minimum time period fromcommencement of a peeling cycle by the peeler device.
 97. The apparatusof claim 93, wherein the sampler is adapted to measure a preset numberof intensity values of the detected electromagnetic radiation; and theoperating system further comprises a calculator for calculating anaverage intensity value representing an average intensity valueassociated with a particular first time period.
 98. The apparatus ofclaim 97, wherein the calculator is arranged to output the averageintensity value to the comparator for comparison against at least oneother calculated average intensity value associated with a differentfirst time period than the particular first time period.
 99. Theapparatus of claim 93, wherein the operating system is adapted to detecta spike of reflected electromagnetic radiation detected by the camera,and to output a calibration signal in response thereto.
 100. Theapparatus of claim 93, further comprising a tuber sorting device coupledto the input of the peeler device for feeding tubers of a selected sizerange to the peeler device.
 101. The apparatus of claim 100, wherein thetuber sorting device comprises a plurality of sorting zones seriallyarranged along a conveying direction from a tuber supply end, whereineach sorting zone comprises an array of mutually aligned bars forming agrid, the bars in each sorting zone being mutually separated by arespective spacing distance, wherein the spacing distance in the firstsorting zone, which is located towards the tuber supply end, is smallerthan the spacing distance in the second sorting zone which isdownstream, along the conveying direction, from the first sorting zone,whereby tubers smaller than a first threshold size fall though the barsof the first sorting zone and tubers larger than the first thresholdsize are conveyed along the bars of the first sorting zone to the secondsorting zone.
 102. The apparatus of claim 100, wherein the tuber sortingdevice further comprises a hopper disposed beneath a respective sortingzone of at least one of the plurality of sorting zones for receivingtubers falling though the bars of the respective sorting zone.
 103. Amethod of peeling tubers, the method comprising the steps of: (a)providing a peeler device defining a cavity surrounded by a peelingmechanism; (b) inputting tubers to be peeled into the cavity; (c)directing electromagnetic radiation from an illumination device into thecavity; (d) detecting electromagnetic radiation reflected into lens of acamera from tubers located in the cavity during a peeling operation bythe peeling mechanism; and (e) operating the peeler device based on thereflected electromagnetic radiation detected by the camera.
 104. Themethod of claim 103, wherein, operating step (e) comprises the sub-stepsof: i. sequentially measuring a plurality of intensity values of thedetected electromagnetic radiation; ii. comparing the measured intensityvalues to determine a rate of change of the measured intensity values;and iii. controlling the peeler device in response to the rate of changeof the measured intensity values.
 105. The method of claim 103, whereinthe operating step (e) terminates operation of the peeler device, eitherimmediately or following a first predetermined time delay, after therate of change of the measured intensity values reaches a first presetthreshold value.
 106. The method of claim 103, wherein the operatingstep (e) causes peeled tubers to be outputted from the cavity, eitherimmediately or following a first predetermined time delay, after therate of change of the measured intensity values reaches a first presetthreshold value.
 107. The method of claim 103, wherein the operatingstep (e) terminates operation of the peeler device, or causes peeledtubers to be outputted from the cavity, either immediately or followinga second predetermined time delay, when the rate of change of themeasured intensity values is below a second preset threshold value atthe expiry of a minimum time period from commencement of a peeling cycleby the peeler device.
 108. The method of claim 103, wherein in sub-stepi a preset number of intensity values of the detected electromagneticradiation is measured; and an average intensity value, representing anaverage intensity value associated with a particular first time period,is calculated.
 109. The method of claim 108, wherein in sub-step ii theaverage intensity value calculated in sub-step i is compared against atleast one other calculated average intensity value associated with adifferent first time period than the particular first time period. 110.The method of claim 102, wherein operating step e comprises thesub-steps of: iv. detecting a spike of reflected electromagneticradiation by the camera; and v. outputting a calibration signal inresponse thereto.
 111. The method of claim 103, wherein the tubersinputted in step (b) are tubers of a selected size range and the methodfurther comprises the step, before step (a) sorting the tubers in atuber sorting device coupled, directly or indirectly, to the input ofthe peeler device, or to the respective inputs of a plurality of peelerdevices, for sorting out the tubers inputted in step (b).